JP2008544471A - Monopolar single plate for fuel cell and fuel cell including the same - Google Patents

Abstract

  The present invention relates to a single extreme plate (4) of a fuel cell having a proton exchange membrane composed of a cathode or an anode monopolar half plate (41) attached to a shielding plate (42). The monopolar half plate includes a cathode or anode active region (411) at the center thereof and at the periphery thereof includes at least two oxidizer boxes when the monopolar half plate is a cathode, or a monopolar If the half plate is an anode, it contains a fuel box. Each oxidant or fuel box includes at least one channel (414) that appears outside the active region (411) to allow oxidant or fuel circulation on the monopolar plate side and outside the monopolar plate. The oxidant or fuel box does not include an opening that appears in the central region of the shielding plate so that the central portion of the shielding plate is not swept away with fuel or oxidant.

Description

  The present invention relates to a monopolar end-plate for a fuel cell having a proton-exchange membrane.

  A fuel cell having a proton exchange membrane is composed of a device that generates electricity by an electrochemical reaction between a fuel such as a hydrogen-containing gas and an oxidant such as an oxygen-containing gas. The fuel and the oxidant are walls made of a solid electrolyte. Separated by the body. In this type of apparatus, if the fuel is a hydrogen gas and the oxidant is an oxygen gas, the hydrogen gas and the oxygen gas react to produce water and at the same time for various uses. Generate available current.

  In general, a fuel cell is made up of reactive cells, each consisting of an electrode / membrane assembly, i.e. a stack of basic cells, the electrode / membrane assembly being fuel on the one hand and the other on the other hand. It is inserted between two bipolar plates having channels for the circulation of an oxidant and finally a heat exchange fluid such as water. The electrode / membrane assembly is made of a multilayer material known per se, and includes a layer composed of a solid electrolyte membrane arranged between two active layers. The active layer includes two outer layers and a diffusion layer. It constitutes the cathode on the one hand and the anode on the other. A stack of basic cells is generally held secured between two terminal plates, said terminal plates extending from one terminal plate to the other and extending through the stack of basic cells. The flange is attached by.

  One end of the fuel cell has an anode monopolar plate with a current collector and the other end has a cathode monopolar plate with another current collector. The assembly is mechanically supported by its terminal plate and tension bar. In general, a single extreme plate is manufactured from a material having excellent corrosion resistance and good conductivity, such as a carbon-containing material such as graphite, a polymer-impregnated graphite, or a flexible sheet of graphite. Is done.

  These components, on the one hand, are usually formed by machining or moulding to define a reactive gas circulation channel on the active surface and a surface in contact with the current collecting plate on the opposite surface. The This technique has the disadvantage that, in particular, it requires the production of specific single extreme plates that are distinct from the bipolar plates that are produced for the cell stack assembly. As a result, the cost increases significantly.

  The object of the present invention is to overcome the above-mentioned disadvantages by providing a single extreme plate for a fuel cell having a proton exchange membrane comprising a bipolar plate. Bipolar plates are composed of bipolar half-plate assemblies that are obtained by drawing and can be manufactured in a more economical manner than known methods of producing single extreme plates.

  In order to achieve this object, the present invention relates to a single extreme plate of a fuel cell having a proton exchange membrane, and the single extreme plate is constituted by a cathode or an anode monopolar half plate fixed to a shielding plate. The monopolar half plate includes an active cathode or anode zone in the central portion thereof, and at the periphery thereof, when the monopolar half plate is a cathode, at least two oxidizer units, or the monopolar half plate. If the plate is an anode, it includes a unit for fuel, each oxidant or fuel unit being outside the active zone to allow oxidant or fuel circulation on the monopolar half plate side to the outside of the monopolar plate. At least one channel that is open to the central portion of the shield plate so that the fuel or oxidant cannot contact the central portion of the shield plate. It does not include any opening which is open to pass.

  Preferably, at least the monopolar half plate includes at least two heat exchange fluid units at the periphery thereof, and the central portion of the monopolar half plate and the central portion of the shield plate cooperate with each other via the connection channel. A space for circulating the heat exchange fluid communicating with the unit is defined. Depending on whether the fixed monopolar half plate is an anode or a cathode, the central portion of the shielding plate can be the same as the central portion of the cathode or anode monopolar half plate, respectively. The shielding plate may be a current collecting plate.

Preferably, the at least one end assembly includes a single extreme plate of the present invention and current collecting means. The current collecting means is, for example, a current collecting plate that comes into contact with a single extreme plate shielding plate.
The end assembly may further include a seal between the perimeter that provides a seal between the single extreme plate and the current collecting means, and a terminal plate.

  The invention will now be described in a more clear but non-limiting manner with reference to the accompanying drawings. The end assembly of the fuel cell shown in FIGS. 1 and 2 includes the terminal plate 1, the current collecting plate 2, the peripheral seal 3, and the active surface 41 and the current collecting plate 2 for cooperating with the reactive electrode / membrane assembly. It is constituted by a stack comprising a single extreme plate 4 having a sealed back surface 42 for contact.

  The single extreme plate 4 is constituted by an assembly part of two half plates 410 and 420. The half plate 410 corresponding to the active surface 41 is a cathode or anode unipolar half depending on whether the end assembly is an assembly for installation at the cathode end or anode end of the fuel cell, respectively. It becomes a plate. The cathode or anode monopolar half plate is the same as the cathode or anode monopolar half plate of the bipolar plate in a fuel cell.

  The cathode or anode monopolar half plate 410 includes an active central portion 411 and an opening 413. The active central portion 411 is constituted by a channel obtained by drawing and is surrounded by a peripheral frame 412. The opening 413 receives an active fluid, which is an oxidant when the monopolar half plate is a cathode half plate, or a fuel when the half plate is an anode half plate. The opening 413 is for circulating the active fluid along the longitudinal direction of the fuel cell, and the channel 414 allows a single pole half to circulate the active fluid reaching through the collector opening 413. Connected to an opening 415 that opens to the outside of the plate, the collector opening 415 constitutes a fluid unit on the surface of the active central zone 411 of the monopolar half plate.

  The monopolar half plate also includes a peripheral opening 416 for the formation of a unit having an active fluid that supplements the active fluid supplied by the fluid unit 413. When the monopolar half plate 410 is a cathode, the fluid unit 416 is intended to provide a cell with fuel, and conversely, when the monopolar half plate is an anode, the fluid unit 416 is intended to transport an oxidant. . These fluid units 416 are not open to the surface of the monopolar half plate, and because of this arrangement, when fluid is supplied to the cell, only the fluid corresponding to the properties of the half plate of the single extreme plate is monopolar. Supplied to the active surface 411 of the half plate 410.

  The second face 42 of the single extreme plate 4 is constituted by a monopolar plate 420 that complements the monopolar plate 410 located on the active face, said active face having a central zone 421 identical to the active central zone of the bipolar plate. Including. The active central region 421 is of a cathode type if the active central band 411 of the monopolar half plate 410 is an anode, and of the opposite type if the half plate 410 is a cathode. The half plate 420 has a peripheral portion 422 that surrounds the central region 421. This peripheral portion 422, like the monopolar half plate 410, includes corresponding openings 423, 426 for cooperating with the openings 413, 416 of the monopolar half plate 410 to form an active fluid unit. The half plate 420 constituting the shielding plate is distinguished from the monopolar half plate only by the fact that none of the openings 423 and 426 constituting the fluid unit are opened outside the central zone 421.

  Therefore, the active fluid transported by the fluid unit formed by the openings 423 and 426 cannot contact the outer surface of the central zone 421 of the shielding plate. The two active central zones 411 and 421 of the monopolar half plate 410 and the shielding plate 420 jointly define a space that allows the heat exchange fluid to circulate. In this space, heat exchange fluid is supplied through openings 417 and 427 which are provided in the periphery of the monopolar half plate 410 and the shielding plate 420 and are intended to form a cooling fluid unit. The cooling fluid unit communicates with a space defining two central zones of the monopolar half plate and the shielding plate through a communication channel.

  All of the resulting plates are plates made from metal that has been cut and drawn to obtain the desired shape, and single pole half-plates that are secured to the shielding plate, for example, are performed especially at the periphery of the plate It is assembled with the shielding plate by welding such as laser welding.

  It will further be noted that the perimeter of the single extreme plate described above is provided so that the seal 3 for sealing the assembly parts can be received. The current collecting plate 2 is made of a flat metal plate for contacting the back surface of the shielding plate 420 in order to collect the current generated by the fuel cell. The collecting plate includes a connecting pin 22 at its central portion that allows the fuel cell to be connected to the operating circuit.

  Finally, the terminal plate 1 consists of a plate whose action is substantially mechanical. The terminal plate 1 has a plurality of openings 10 in its peripheral portion for receiving, for example, a tension bar, which serves to fix the stack constituting the fuel cell, between the cathode-side terminal plate and the anode-side terminal plate. In addition, the terminal plate includes a hole 11 at the center for allowing passage of the electrical connection pin 22 so that the fuel cell can be electrically connected outward.

  A variety of variants can be used to produce the previously described stacks, in particular the openings on the periphery of the monopolar plate that are not intended for the supply of active fluid are sealed off. Also good. Further, for example, the connection pin outside the fuel cell may be directly fixed to the shield plate of the single extreme plate. In this case, the shielding plate itself constitutes a current collecting plate.

It is the exploded back perspective view seen from the diagonal of the end assembly parts in the fuel cell which has a proton exchange membrane. FIG. 2 is an exploded front perspective view of an end assembly component in the same fuel cell as shown in FIG.

Claims (7)

  A single extreme plate (4) of a fuel cell of the type having a proton exchange membrane, wherein the single extreme plate is constituted by a cathode or anode monopolar half plate (41) fixed to a shielding plate (42), The half plate includes an active cathode or anode zone (411) in the central portion thereof, and at the periphery thereof, when the monopolar half plate is a cathode, at least two oxidant units (413) In the case where the half plate is an anode, a unit for fuel is included, and each fuel or oxidant unit has an active zone (to allow circulation of oxidant or fuel on the monopolar half plate side and outside the monopolar plate). 411) including at least one channel (414) that opens to the outside, so that the oxidant unit or fuel unit cannot contact the central part of the shield plate with fuel or oxidant. Single endplate, characterized in that does not include any opening which opens into central zone of the shield plate.   At least the monopolar half plate (41) includes at least two heat exchange fluid units (417) at the periphery thereof, and the central portion (411) of the monopolar half plate (41) and the central portion of the shielding plate (42) ( 421) jointly defines a space for circulation of heat exchange fluid that communicates with the heat exchange fluid unit via a connection channel.   Depending on whether the monopolar half plate to be fixed is an anode or a cathode, the central portion (421) of the shielding plate (42) is identical to the central portion of the cathode or anode monopolar half plate, respectively. The single extreme plate according to claim 2.   The single extreme plate according to any one of claims 1 to 3, wherein the shielding plate is a current collecting plate.   5. A fuel cell of the type comprising an alternating stack of electrodes / membranes and bipolar plates secured between a cathode end assembly and an anode end assembly, wherein at least one end assembly is according to claims 1-4. A fuel cell comprising the single extreme plate (4) according to any one of claims 1 and current collecting means.   6. The fuel cell according to claim 5, wherein the current collecting means is a current collecting plate (2) in contact with a shield plate (42) of a single extreme plate.   The end assembly further comprises a seal (3) between the perimeter that provides a seal between the single extreme plate (4) and the current collecting means (2), and a terminal plate (1). Item 7. The fuel cell according to Item 5 or 6.

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